Using animals to harvest forage crops, such
as irrigated pastures, requires much less
labor and equipment than hay and feeding
operations and allows for an increase in net
farm income. But there are numerous other
uses for irrigated pastures that are not
driven by generating income. In many areas,
small tracts are used to pasture horses or
hobby livestock. Ranchers use irrigated
pastures as holding sites, calving pastures,
horse pastures, hay sources or supplemental
rangeland grazing.

To assist New Mexico’s irrigated pasture
producers with selecting and establishing
pasture species, New Mexico State University’s
Agricultural Experiment Station has conducted
research throughout the state and
accumulated information from other states
and producers. That information is presented
here as a guide to developing productive,
irrigated pastures in New Mexico. These
recommendations might change as more
data and improved species become available.

Circular 586, “Grazing Systems and
Management for Irrigated Pastures in New
Mexico,” and other resources that provide
more information about topics covered here
are available from your county Cooperative
Extension Service office or through New Mexico State University’s Agriculture, Consumer and Environmental Sciences Web site at www.aces.nmsu.edu/pubs. Several are mentioned by name in
this publication.

Pasture Species Selection

Several factors must be considered in pasture
species selection that fall into two broad
categories—local adaptation and intended
use. Within those two categories, there are
some questions producers should answer
before developing their forage program.

How long will this land be in pasture?

Pasture cropping systems generally fall into
three categories: permanent, annual and
rotational. Permanent pastures usually consist
of perennial species that remain on the site
indefinitely. Benefits of permanent pastures
include establishment costs prorated over a
longer period, soil and water conservation
and soil improvement, particularly on
marginal land. Annual pastures are planted
for seasonal use. They can be used to
supplement permanent pastures during times
of low forage productivity, or they may
constitute the entire forage program. Many
producers prefer to use a combination of
annual species year-round for pastures,
because they provide a valuable source of
high-yielding, nutritious forage. While
annual species generally yield more than
permanent pastures, the additional cost of
land preparation, seed and planting each year
could more than offset any differences in
production. Irrigated pastures that will be
rotated with row crops are part of a rotational
cropping system. The forage species used in this situation, whether annuals or perennials,
cool-season or warm-season, depends on the
length of the rotation, season of the year and
the desired amount of forage produced.

What kind of animals will graze
the pasture?

Different animal species and classes of
animals within each species have different
nutrient requirements (Figure 1). Animals that
have high nutritional demands, such as
working horses, lactating cows or growing
steers, need greater amounts of higher-quality
forage. But, in the case of horses, if quality is
too high and fiber too low, colic can be a
problem. Also, if the pasture will be managed
only for aesthetics or as a low-maintenance
turf, less productive pasture species might be
more desirable. Additionally, different animal
species apply different kinds of grazing pressure to pastures. Some, like beef cattle,
graze uniformly across a pasture. Others,
such as horses, spot graze, leaving some areas
to become overmature and overgrazing other
areas. Finally, while legumes usually are
higher in yield and quality than grasses, some
legumes cause bloat in ruminants, which can
lead to death. Producers need not avoid
legumes entirely, but they do need to manage
pastures with legumes to lessen the likelihood
of the occurrence of bloat. More information
about bloat and protecting animals against
bloat is presented in Circular 586.

What forage crop species
can be grown?

New Mexico has vast differences in elevation
and latitude. The wide range of climatic
conditions allows for a broad range of species
that may be adapted when irrigated. Pasture species discussed later in this publication are
known to be well-adapted to the state and
have value as livestock feed. The description
of each species includes limitations on
adaptation. Other considerations in
determining adaptability are the types of
insects and weeds found in the area to be
used for pasture. Not many pesticides are
labeled for pasture use. Soil type also plays a
key role in selecting pasture species. Species
performance can be affected greatly by poor
or excessive drainage, soilborne diseases and
nematodes, soil depth, soil pH and salinity.
The U. S. Department of Agriculture soil
survey and a soil analysis will help determine
the soil constraints on your property that
should be considered when selecting irrigated
pasture species. Once the pasture species are
selected, variety selection also can be a critical
decision based on the same criteria as that used for species selection. Contact your local
county Cooperative Extension Service for
more information.

Description of Pasture Species

Species types. Forage species usually are
classified by their growth characteristics—
when they grow, how long they live and how
they spread. Cool-season species grow best
between 60° and 80° F. Warm-season species
grow best between 80° and 95° F. Most
warm-season species are killed when
temperatures consistently fall below 10° F.
Annual species complete their life cycle in
one year or less, biennials need two growing
seasons or years to complete their life cycle.
Species that persist for three or more years are
considered perennial. Generally, cool-season
species are higher in quality than warm-season
species, annuals are higher in quality than perennials, and legumes are higher in
quality than grasses (Figure 1).

Seasonal yield distribution is another
factor to consider when making species
selections so that forage production will
match animal demand (Figures 2-3). Cool-season
perennial species generally have their
highest production in the spring, followed by
a summer slump and another growth period
in the fall. If irrigation water is available only
during the growing season, alfalfa yields will
be lower early in the season and sustained
during the summer (Figure 4). Cool-season
annuals grow some in the fall, followed by a
period of dormancy or minimal growth in
the winter and highest production in the
spring. Generally, warm-season annuals and
perennials grow actively from mid-May until
a hard freeze in the fall. Peak production
generally is in mid-summer.

Most species will spread by seed.
Otherwise, some species have a bunch-type
growth habit and spread by tillering or
crown expansion (i.e. tall wheatgrass, tall
fescue). Other species reproduce vegetatively,
with lateral stems either belowground
(rhizomes) or aboveground (stolons) that can
form new plants by rooting at nodes. In
addition to spreading by seed, Johnsongrass
(normally considered a weed) spreads by
rhizomes; buffalograss spreads by stolons.
Bermudagrass can spread by rhizomes,
stolons and seed.

Forage crops described in this
publication include grasses and legumes. All
forage crops need nitrogen for maximum
productivity, but legumes live in cooperation
(symbiosis) with certain nitrogen-fixing
bacteria (rhizobia), which form nodules on
the roots and convert atmospheric nitrogen
into a form the plant can use. For this
reason, little or no nitrogen fertilizer is
necessary for legumes. Grasses do not have
this capability and must have their nitrogen
requirement met by other means.

Another difference between most grasses
and legumes is their potential to cause frothy bloat in ruminants. Cool-season, annual
grasses, such as small grains and most
legumes, can cause bloat; animals grazing
pastures including these species should have
a bloat preventive available at all times.

Finally, grass tetany, caused by
magnesium deficiency, can occur if soils are
low in magnesium. This disease is most
common in monoculture grass pastures
during periods of rapid growth from fall
through spring. Some grass species are more
likely to cause grass tetany, generally because
they are poor magnesium accumulators or
they have a period of extremely rapid growth
in the spring. More information on grass
tetany is given in Circular 586.

Mixtures. Grass-legume mixtures
generally are preferred over monocultures.
Because forage yield and quality usually
increase, seasonal distribution can become
more uniform (Figure 4). And the legume
supplies nitrogen to the grass, reducing
fertilizer costs. Also, if the grazed material
from the pasture is at least 50 percent grass,
the incidence of bloat is reduced.

Furthermore, using grass-legume mixtures
can reduce the likelihood of grass tetany
mixtures, because legume forage generally
is higher in magnesium.

With few exceptions, the legumes
described in this publication should be
used in pastures as mixtures rather than
monocultures. Simple mixtures (no more
than two grasses and/or two legumes) are
better than complex mixtures, because
complex mixtures present several problems.
Differences in requirements for cultural
practices (harvest timing, fertility,
irrigation); grazing management; and ability
to compete for light, water, nutrients and
space make it difficult to maintain all
species in the stand. Additionally, animals
will selectively graze more palatable species
and eliminate them from the stand, leaving
less palatable species to become overmature.

While mixing perennial cool- and
warm-season grasses in the same pasture
has not been successful in most irrigated
areas, including perennial cool-season
legumes in warm-season grass pastures has been successful in the Southeast
and some testng has been done in
New Mexico (NMSU Research Report 167).
Overseeding dormant, warm-season
pastures, such as bermudagrass, with
annual cool-season grasses like annual
ryegrass or legumes also has been
successful. However, in these mixtures,
the warm-season grass needs to be going
dormant prior to planting in the late
summer, and the cool-season species
should be grazed or killed before the
warm-season grass greens up in the
spring. The availability of irrigation
water for establishment and early
spring production might be a concern
in many areas of the state.

Most of the forage crop species listed
in this publication have demonstrated
adaptation and are prominently used in
irrigated pastures in New Mexico. A few are
included that have not yet been widely used
but show promise. Other species might be
well-adapted, but are not included because of
low productivity, insurmountable antiquality
factors or they simply might not be as
well-adapted as the species listed in this
publication. Specific varieties are not listed
because of differences in seed availability
and local adaptation.

Perennial Cool-Season Legumes

Alfalfa (Medicago sativa) is a long-lived
species that continues to be the legume of
choice in most irrigated pasture situations.
The plant grows erect with shoots rising from
the crown. Grazing might damage the crown,
providing an entry for disease organisms.
However, grazing pressure has been used to
develop many newer varieties. These varieties
have a crown located below the soil surface
where it is protected from trampling effects.
They also have broader crowns and taproots
that maintain a higher carbohydrate reserve
and shoots that produce leaves below the
grazing horizon, so that the plants can
continue to photosynthesize while being grazed. Alfalfa is a high-yielding, nutritious,
palatable species, but the possibility of bloat
in ruminant animals exists, even in grazing-tolerant
varieties.

Alfalfa is adapted to most regions
of New Mexico. It grows best on loamy,
fertile, well-drained soils, but it grows on
most soil types. Once established, it can
tolerate a considerable amount of salt and
has more heat tolerance than most coolseason
forage legumes. Alfalfa produces
high yields as a monoculture but also
performs well when mixed with many
grasses. If planted as a monoculture, use
15 to 20 pounds per acre. For mixtures,
use only 4 to 5 pounds per acre.

Alfalfa is allelopathic. That is, when a
stand is more than a year old, a compound
is released into the soil that kills or stunts
newly germinated alfalfa seedlings. This
toxic compound remains in the soil for
approximately one year after all the alfalfa
is gone. So, once alfalfa is no longer
contributing enough to pasture yield and
quality, renovation with another legume,
such as birdsfoot trefoil or red clover, is
advisable. After one year, alfalfa can be
reestablished successfully. Otherwise, the
entire pasture should be rotated to an annual
crop for at least one complete growing
season, so that tillage and irrigation practices
can help dissipate the toxic compound.

Alfalfa varietal performance is tested
at several locations each year in New
Mexico. The results of those tests and
variety selection guidelines are available
in an annual report from your county
Cooperative Extension Service or on the
Web at www.aces.nmsu.edu/pubs.

Birdsfoot trefoil (Lotus corniculatus) is a
biennial or short-lived perennial with a
semierect to prostrate growth habit. It is
adapted only to the state’s cooler regions or
higher elevations, because it lacks heat
tolerance. Birdsfoot trefoil is adapted to most
soil types and can be grown on heavy, poorly
drained or swampy soils unsuited for most other legumes. Birdsfoot trefoil has good
tolerance to flooding and salinity. It is
considered nonbloating, but bloat can occur on
rare occasions. Birdsfoot trefoil does not have
the yield potential of alfalfa and other legumes.
While it is best-suited for mixing with grass,
yield of the mixture is usually similar to that of
a properly fertilized monoculture of the
associated grass. Birdsfoot trefoil should be
sown at 4 to 6 pounds per acre in mixtures. It
should be managed to permit natural reseeding
at least every other year so that new plants can
replace those that die.

Cicer milkvetch (Astragalus cicer) has a
creeping, rhizomatous growth habit. It is
drought-tolerant, but must be irrigated to
maintain stands in most of New Mexico.
Cicer milkvetch is nonbloating, but it does
cause photosensitivity (sunburn) in livestock.
Seedling emergence and growth is slower
than either alfalfa or sainfoin. It generally
does not perform well in mixed pastures and
should be used only as a monoculture in
which it will produce approximately half the
yield of alfalfa. Additionally, persistence of
cicer milkvetch under grazing has been
questioned. However, for low-maintenance
situations or rotational stocking with a
longer rest (45-60 days) period, cicer
milkvetch might perform satisfactorily. The
seeding rate for monoculture cicer milkvetch
is 5 to 8 pounds per acre.

Kura clover (Trifolium ambiguum) is
rhizomatous and long-lived. It is very similar
in appearance to white clover, but plants are
larger. Kura clover establishment is directly
related to the number of plants that nodulate,
but it does not nodulate well in the field.
Therefore, when seeding kura clover, it is
crucial to use properly inoculated seed
(described later in this publication) or to use
seed that has been factory treated within the
previous year. This species is slower to
establish than most other legumes. However,
once established, kura clover is an aggressive
spreader. It even overtook tall fescue sown at
the same time in a trial in north-central New Mexico at NMSU’s Sustainable Agriculture
Science Center at Alcalde. In that study, it
yielded as well as alfalfa after four years and
was still maintaining stand and yield after
eight years when the trial was concluded.
In trials in eastern New Mexico, at the
Agricultural Science Center at Tucumcari,
kura clover did not perform as well as it had
in north-central New Mexico, indicating that
its adaptation area might be limited to the
higher elevations of northern New Mexico.
Like white clover, most of the grazed
material is leaf and, therefore, higher in
quality than alfalfa. But it can cause bloat.

Kura clover establishes well when sown
in mixtures. It is likely that drilling the kura
clover in rows (10 pounds per acre for
mixtures) and broadcasting the associated
grass on the soil surface would help enhance
stand establishment. Data indicates that
initial yields will be mostly grass that will
provide grazing until the kura clover is
established. Once established, kura clover
will become dominant in the stand. Bloat
preventives should be provided to animals
grazing pastures that include kura clover,
even in the early years when the stand is
greater than 50 percent grass. Although
high-yielding, kura clover does not tolerate
frequent defoliation and should be
rotationally stocked with a long rest interval
(45 to 60 days).

Red clover (Trifolium pratense) generally
is a biennial or short-lived perennial that
might act as an annual in some areas. It has
an erect growth habit. The leaves usually are
covered with hair. Red clover does not
tolerate frequent close grazing. However,
in a rotational stocking system similar in
frequency to that of hay management
(30 to 45 days), it can perform quite well.
Red clover does best on fertile, well-drained
soils with a moderate pH range (6 to 8). It is
adapted to the state’s cooler regions
(northern half or higher elevations in the
south). Diseases common to red clover
contribute to its short life span in other areas but might not be prevalent in New Mexico’s
well-drained soils. Four-year-old stands of
red clover at NMSU’s Agricultural Science
Center at Tucumcari still yielded comparably
to two-year-old stands without reseeding.
Bloat is a severe problem with red clover, but
it is compatible with several cool-season
grasses. Although red clover usually is a shortlived
species, stands can be maintained by
allowing it to reseed naturally approximately
every other year. Use 8 to 12 pounds per acre
when seeding monoculture red clover or 4 to
6 pounds for mixtures.

Sainfoin (Onobrychis viciaefobia) has a
growth habit similar to that of alfalfa, but
production has been limited to early to
midspring. Sainfoin’s stand persistence has
been questionable in many situations,
especially when grown under intense
irrigation. Sainfoin’s crown is weak and will
not tolerate trampling by grazing animals, so
it should be planted in rows to reduce
trampling, if used in pastures. Sainfoin
requires a well-drained soil and is adapted to
calcareous and sandy or cobbly soils that
might be unsuitable for other forage
legumes. It is resistant to the alfalfa weevil.
But is susceptible to many other alfalfa pests
as well as Lygus bugs. Sainfoin also is
susceptible to root and crown diseases. It is
nutritious, highly palatable and nonbloating.
These qualities make sainfoin susceptible to
overgrazing if not managed properly. It is
compatible with many cool-season grasses
but also makes an excellent pasture as a pure
stand. Sainfoin is not an efficient nitrogen
fixer and might suffer a midseason slump in
production due to nitrogen deficiency.
Seeding rates for sainfoin are 35 to 40
pounds per acre as a monoculture and 20
pounds per acre in mixtures.

Strawberry clover (Trifolium
fragiferum) is a long-lived, stoloniferous
perennial. Because it is a very low-growing
species, it is well-suited for grazing, but
not for hay production. While strawberry
clover is adapted best to the state’s cooler regions, it has fair heat tolerance. It also
has good salt tolerance and prefers wet
soils with high pH. Strawberry clover is
not used widely for irrigated pastures in
New Mexico, but it has potential for low maintenance
areas and is compatible with
many cool-season grasses. Use 2 to 3
pounds per acre when seeding strawberry
clover as a monoculture or in mixtures.

Sweetclover (Melilotus officinalis and
M. alba) includes species that are cool-season
biennials or annuals with a very erect
growth habit. Plants in these species usually
grow to heights of more than 2 feet with
stems that are coarse and become woody
toward maturity. Sweetclover not only
causes bloat, but also contains a chemical
called coumarin, which has an undesirable
taste, affecting palatability. Coumarin can
be converted to a toxic substance that
reduces the blood’s clotting ability, causing
animals to bleed to death from slight
wounds or internal hemorrhaging.
Sweetclover also has a very low leaf-to-stem
ratio, which affects both quality and yield.
Although it is adapted to most soil and
climatic conditions in the state and is an
excellent green manure crop, sweetclover
generally is not recommended as a pasture
species because of its antiquality factors.

White clover (Trifolium repens var.
giganteum), a biennial or short-lived
perennial has a creeping, stoloniferous
growth habit. White clover tolerates
frequent close grazing and trampling by
livestock. It is adapted to a wide variety of
soil types and will grow on poorly drained
soils, but it does not tolerate salinity. Stolon
and root rot diseases can deplete white
clover stands. It also is susceptible to leaf
diseases and root knot nematodes, although
some varieties have tolerance to nematodes.
Like alfalfa, white clover can cause bloat. It
can be grown in most areas of New Mexico,
but it is best-adapted to the northern half of
the state and higher elevations in the
southern half. The various white clover types are well-adapted to grazing. But
because of their prostrate growth habit, they
are not well-suited for hay. White clover is
compatible with most cool-season bunch
grasses and should be sown at 2 to 3 pounds
per acre in mixtures.

Perennial Cool-Season Grasses

All perennial cool-season grasses described in
this publication are compatible with legumes.
Unless otherwise specified, seeding should be
15-20 pounds per acre rates for monocultures
and 12-14 pounds per acre for mixtures.

Altai wildrye (Elymus angustus) is a
rhizomatous species that looks like a
bunchgrass. Tests at Tucumcari, have shown
it to be widely adapted to well-drained and
poorly drained, high saline soils. It was
among the highest-producing, cool-season
grass species, giving greater summer and lateseason
yields than tall wheatgrass and tall
fescue. Leaf blades are wide, similar to tall
fescue, and coarse like tall wheatgrass with a
sharp point. However, cattle grazing plots
that included several cool-season grasses
appeared to have a similar preference for altai
wildrye as for tall wheatgrass. Because this
species holds promise for increasing late-season,
cool-season grass pasture
productivity, more research is needed to
determine how broadly adapted it is to New
Mexico and the best management practices
for its use here.

Orchardgrass (Dactylis glomerata) has a
bunch-type growth habit. It is adapted to
New Mexico’s cooler regions and tolerates a
wide range of soil conditions, but prefers
fertile, well-drained soils. Orchardgrass is
palatable when fertilized well and grazed
frequently. It is one of the more widely used
pasture grasses at the higher elevations in
northern New Mexico, but it is not as hardy
or long-lived as tall fescue or tall wheatgrass
and is not very salt-tolerant. Orchardgrass
also is a poor accumulator of magnesium,
and grass tetany can be a problem (see Circular 586).

Perennial ryegrass (Lolium perenne) is a
short-lived perennial with a bunch-type
growth habit that can reseed when managed
properly. However, ergot can reduce seed yield
and quality and limit reseeding. Of all the
cool-season grasses used in New Mexico,
perennial ryegrass appears to be the most
sensitive to cold, heat and drought. Best
adapted to New Mexico’s cooler regions, it
prefers fertile, well-drained, medium-textured
soils with nearly neutral pH. Perennial
ryegrass generally is not recommended for
New Mexico pastures.

Russian wildrye (Elymus junceus) is a
long-lived, bunchgrass. In tests at Tucumcari,
it was the most drought-tolerant of the cool-season
grasses and responded quickly to
precipitation. Russian wildrye is a lowgrowing
species that produces seedheads
early and remains vegetative for the rest of
the year, maintaining fine leaves that are
palatable and high in quality. Because it is
low-growing, it is not well-suited for hay
production. This species might have value in
low-input, low-stocking density systems in
the northern half of New Mexico, but
production can be increased with irrigation
and fertilization.

Smooth bromegrass (Bromus inermis) is
a rhizomatous perennial with an erect growth
habit. It has an adaptation area similar to
that of orchardgrass and is used mainly in
the higher elevations of northern New
Mexico. Smooth bromegrass might tolerate
periods of drought, temperature extremes
and salt better than orchardgrass. But it
tends to become sod-bound because of heavy
rhizomes, which can reduce productivity. To
overcome this, stands may need to be
renovated by disking or chiseling every three
to five years to improve air, water and
fertilizer infiltration.

Tall fescue (Festuca arundinacea) is a
long-lived species with a bunch-type growth
habit, although it is weakly rhizomatous and can form a dense sod over time. Tall fescue
can be grown throughout New Mexico, but
it performs best in the northern half of the
state, particularly along the Rio Grande and
Pecos corridors. It is adapted to a wide
variety of soil types and pH, tolerating wet,
poorly drained soils as well as moderate
drought, heat and shade. Tall fescue is quite
tolerant to grazing and management stresses.
Although it might be less palatable than some
cool-season grasses, livestock will graze it and
perform well, when it is fertilized properly
and grazed frequently. Tall fescue is
compatible with most cool-season legumes
in mixtures.

Tall fescue endophyte. Poor animal
performance on tall fescue pasture has
been linked to a fungus, Acremonium
coenophialum, found within the plants
(endophytic) that is only transmitted
through the seed. This endophyte causes
tall fescue plants to make alkaloids that are
associated with their ability to withstand
mismanagement and other stress factors. But
the alkaloids also have been linked to poor
animal performance. Producers who want to
know the endophyte status of their tall fescue
pastures can submit a plant sample for
analysis. Contact your county Cooperative
Extension Service office about the sampling
technique and laboratories that conduct
analysis. Because the endophyte is more
active in reproductive tillers, declines in
animal performance can be reduced or
avoided by maintaining the tall fescue in a
vegetative state. This can be accomplished
by grazing until approximately early May,
when seedstalk elongation begins, and
clipping after grazing to remove the
seedstalks. Additionally, anytime the tall
fescue is stressed from heat or drought,
the endophyte’s negative effects will be
magnified.

Endophyte-free varieties that perform as
well as the older, endophyte-infected varieties
are available. These cultivars might not stand up as well under ismanagement, such as
overgrazing or drought. One variety that has
a beneficial endophyte has not been shown
to cause poor animal performance.

Tall wheatgrass (Agropyron elongatum) is
a long-lived bunchgrass that, like tall fescue,
can form a dense sod. While most perennial
cool-season grasses decline in quality and
palatability when mature, tall wheatgrass
does more so than other species. It is adapted
to a wide range of soil types and has the best
salt tolerance of most perennial cool-season
grasses described in this publication. Tall
wheatgrass can withstand frequent grazing
but not overgrazing. Although it is adapted
to most of New Mexico, its primary use will
be in the lower elevations of the state’s
northern two-thirds.

Timothy (Phleum pratense) is a biennial
bunchgrass adapted to the higher elevations
of northern New Mexico. It exhibits
perennial characteristics by vegetative
reproduction. Timothy provides high-quality
forage for hay or pasture but will not persist
under close, continuous grazing; is not heator
drought-tolerant; and recovers slowly
under limited moisture.

Because it is a biennial, managing
timothy is critical to stand maintenance.
To allow sufficient storage of carbohydrates
important to vegetative reproduction, the
first harvest each year should occur between
flowering and the soft-dough stage. This is in
contrast to most other cool-season grasses,
which should be harvested at the early
head stage to maximize yield and quality.
Additionally, even more crucial than for all
other cool-season grasses, nitrogen should be
applied to timothy more frequently, but in
lesser amounts. This species produces two
generations of tillers each year, the second of
which overwinters and becomes the primary
growth for the following year. To encourage
second generation growth in both years,
nitrogen needs to be available in the fall and
early spring. Without split applications, poor fall growth will occur and even poorer
regrowth the next spring. Management
similar to that which maximizes yield and
quality of other cool-season forage grasses,
namely higher applications of nitrogen and
early harvest, will consistently reduce
timothy stands. The seeding rate is 8 to 14
pounds per acre for monoculture timothy
and 4 to 6 pounds per acre for mixtures.

Perennial Warm-Season Legumes

There are no perennial, warm-season legumes
known to be suitable for use in New Mexico’s
irrigated pastures. Sericea lespedeza
(Lespedeza cuneata) and perennial peanut
(Arachis glabrata) are examples of perennial
warm-season legumes used elsewhere.
However, sericea lespedeza performs poorly
in calcareous soils, such as those prevalent in
New Mexico. Additionally, production
potential by perennial peanut is reduced after
long, cool spells and it winterkills at 15° F.

Perennial, Warm-Season Grasses

Bermudagrass (Cynodon dactylon)
establishes rapidly compared with most
perennial warm-season grasses and forms a
dense sod, spreading by both rhizomes and
stolons. It favors medium- to light-textured
soils and is very salt- and drought-tolerant.
Bermudagrass responds well to fertilizer and
can stand heavy applications of animal
waste. It has poor shade tolerance and is not
compatible with many other grasses or
legumes, but might mix well with alfalfa.
Bermudagrass is sensitive to cold; growth
slows or ceases when night temperatures fall
below 60° F. Therefore, bermudagrass grows
best at the lower elevations found in the
southern two-thirds of New Mexico. While
winterkill has been a problem for bermudagrass
in New Mexico, newer varieties are
available that are more cold-tolerant.
Bermudagrass can be established either
vegetatively (with sprigs) or by seed.
Sprigging is more expensive than seeding but might give quicker fill,
even when sprigs are placed on
3-foot centers.

Some bermudagrass varieties are
available only as sprigs, because they do not
produce large quantities of seed or the seed is
not true to the variety. Most of these are
ecotypes that might be well-adapted and
productive near their area of origin.
However, the farther away from their point
of origin they are grown, the less productive
they tend to be with the same level of
fertilizer and water inputs. The Natural
Resources Conservation Service has plant
materials centers located around the country.
These centers, including one located at
NMSU’s Agricultural Science Center at Los
Lunas and another in Woodward, Okla.,
have tested many bermudagrass ecotypes
and can provide information about the
adaptation area of many varieties, as well as
many other forage crop species. As is the case
with all forage crops, some companies have
not had their bermudagrass varieties
independently tested by universities over a
broad range of environments. Before buying
planting material (sprigs) of any
bermudagrass variety, always ask if university
data is available for that variety. Sprigged
bermudagrass varieties should be planted at
15 to 20 bushels per acre. If a seeded type is
selected, plant 5 to 10 lb per acre.

Blue grama (Bouteloua gracilis) is a
native range bunchgrass that has been
improved for use in irrigated pastures.
Because of its rangeland background,
improved blue grama is probably better
suited for limited irrigation and limited
nitrogen situations than the other perennial
warm-season grasses, which are all
introduced species, listed in this publication.
Although some seedstalks can be 1 to 3 feet tall, blue grama leaves remain closer to the
ground, so it is not well-suited for hay
production. Additionally, blue grama quality
will likely be better maintained in low-input
systems and after the growing season.
Productivity also will be lower. Blue grama
can grow throughout New Mexico. It should
be sown at 1 to 1.5 pounds pure live seed
(PLS) per acre, using a drill with a fluffy
seed box.

Kleingrass (Panicum coloratum) is a
bunchgrass introduced to the United States
from Africa. It is fine-stemmed and leafy and
grows to a height of 3-4 feet. Kleingrass
spreads by tillering and short rhizomes. It
also can establish roots at nodes on the stems
that come in contact with the soil, an effect
called layerage. Kleingrass is adapted to a
fairly wide range of soil and climatic
conditions. However, there are some
concerns about its cold tolerance. Although
it has been grown successfully during a
period of mild winters at Tucumcari, it
currently is recommended for use only in the
southern half of the state. Kleingrass can
cause photosensitization (swellhead) in
white-faced sheep. The seeding rate for
kleingrass is 1.5 to 2 pounds PLS per acre.

Old world bluestem (Bothriochloa
ischaemum) is a bunchgrass that was
introduced from eastern Europe and Asia.
This species is not as salt-tolerant as
bermudagrass and prefers well-drained soils.
Growth is initiated later in the spring than
bermudagrass and is sustained later in the
summer, when other species are not as
productive or are dormant. Establishment
can be slow, but good stands can be achieved
in one season under good management and
optimum conditions. Initially, old world
bluestem does not compete well with weeds
or other species when sown in mixtures.
Once established, it is very competitive,
spreading by crown expansion and seed.
During peak production periods, livestock
might not be able to prevent old world bluestem from forming seedheads.
Concentrating animals in a smaller part of
the pasture and harvesting excess forage as
hay might help resolve this problem. When
seeding old world bluestem, plant 2 to 3
pounds PLS per acre using a drill with a
fluffy seed box.

Cool-Season Annual Legumes

Berseem clover (Trifolium alexandrinum)
has been grown at Tucumcari, even though
it was originally not known to be a winter-hardy
species and has not been previously used
in New Mexico. It has an erect growth pattern
and is very tolerant of alkalinity, salinity and
poor drainage. Berseem clover produces high quality
forage that is nonbloating. It can be
grazed when it reaches 10 inches and will
continue producing new growth if a 3- to
4-inch stubble is maintained. Although
berseem clover did not produce viable seed in
the planting at Tucumcari, newer varieties
have been managed for natural reseeding in
other areas by removing animals during the
bud stage. Once seed is produced, grazing can
resume to remove all standing residue and to
form good seed-to-soil contact for late summer
germination. The seeding rate for
berseem clover is 20 pounds per acre.

Hairy vetch (Vicia villosa) is widely
adapted to New Mexico’s climate. It has a
vinelike growth habit and can be grown as a
monoculture or overseeded into dormant,
perennial, warm-season grasses. Hairy vetch
does not yield well in the fall, but it can
provide four to six weeks of grazing in the
early spring before the warm-season grasses
break dormancy. Hairy vetch will reseed
naturally if cattle are removed prior to the
bud stage. As with berseem clover, once the
seed is produced, grazing can begin on new
growth of the warm-season companion grass
or residue from the hairy vetch. Initial
seeding rate for hairy vetch is 20 to 40
pounds per acre.

Cool-Season Annual Grasses

Annual (Italian) ryegrass (Lolium
multiflorum) is similar to perennial ryegrass,
except it completes its life cycle in one
season. Annual ryegrass has been used
successfully as a winter annual pasture in
southern New Mexico. This species performs
well in the southeastern United States, when
sown into dormant, warm-season grass
pastures. Use a no-tillage drill when
overseeding dormant, warm-season grass
pastures to achieve good seed-to-soil contact,
which promotes germination and
establishment. Seeding rates of 20 to 30
pounds per acre should be used for
monocultures or overseeding operations.

Small grains include barley (Hordeum
vulgare), oats (Avena sativa), rye (Secale
cereale), wheat (Triticum aestivum) and
triticale (Triticum secale). Barley and oats are
somewhat more susceptible to cold
temperatures and historically have been
recommended only for southern New
Mexico. But newer varieties of both have
been grown successfully for pasture and hay
in recent years at Tucumcari. Rye, wheat and
triticale are more cold-tolerant and have been
used more in the cooler regions. Barley and
rye generally produce more forage than
wheat or oats in the fall. Barley appears to be
the most salt-tolerant of these crops, while
rye generally performs better than the others
on sandy or poor land. Mixtures of small-grained
species are not desirable, because
selective or spot grazing is likely to occur.
In grazing preference trials at Tucumcari,
oats were selected over other small-grained
species (barley, rye, triticale and wheat).
Performance by animals grazing monocultures
will likely be similar across
small-grained species.

Some newer varieties of spring oats also
have survived winters at Tucumcari and are
very productive in the fall. A mixture of those
varieties and winter oats might increase fall
productivity without the selective grazing
problem. A better option is to plant a pasture with spring oats for fall grazing, a second
pasture with winter oats for spring grazing and
a third pasture with rye as a rescue pasture for
winter and early spring grazing.

Small grains should not be grazed until
they are 5 to 6 inches tall, allowing the plants
to establish a good root system. Grazing too
soon or too close to the ground slows root
development and decreases the plant’s ability to
survive the winter and be productive in the
spring. Animals should be removed when the
forage has been grazed to a height of 2 inches.
Small grains can provide grazing in both the
fall and the spring and still produce a grain
crop if grazing is halted in mid-March or at the
first sign of stooling. If the crop is not to be
harvested for grain, grazing can continue until
forage becomes limiting, which can be well
into May. Rotational stocking or deferred
(strip) grazing might be valuable for providing
higher levels of high-quality feed during
periods of low productivity (December to
February) and to extend grazing beyond mid-May. Two pastures with two-month rest
periods might be satisfactory for stand recovery
and productivity. Seeding rates for smallgrained
species in irrigated pastures should be
60 to 100 pounds per acre. Nitrate toxicity,
which will be discussed in more detail later, can
be a problem when using small grains pastures.
Bloat is another concern, especially after a
freeze or during rapid growth in the spring.
Grass tetany also can be a problem during
rapid spring growth (see Circular 586).

Warm-Season Annual Legumes

Warm-season annual legumes have not
been tested broadly in New Mexico for use
in irrigated pastures. But a few, such as
cowpea (Vigna unguiculata), lablab (Lablab
purpureus) and tepary bean (Phaseolus
acutifolius), might have value when mixed
with a warm-season annual grass and
intensively, rotationally stocked to maximize
productivity. Seeding rates for warm-season
annual legumes are 60 to 100 pounds per
acre as monocultures or mixtures.

Warm-Season Annual Grasses

Sorghums and sorghum × sudangrass
hybrids (both Sorghum bicolor) provide
valuable temporary pasture in lower
elevations throughout New Mexico
(below 6500 feet). These forages respond
well to nitrogen fertilization and irrigation,
producing high yields of palatable forage.
Sorghum forage quality has been improved
by including the brown midrib and
photoperiod sensitivity traits. Brown
midrib (BMR) varieties have a lower lignin
concentration that increases available energy
and digestibility. Heading in photoperiod
sensitive varieties is not initiated until
approximately mid-September when day
length decreases. This broadens the harvest
window, allowing for higher yields of highquality
vegetative forage. Seeding rate also
can affect quality. Plants from higher
seeding rates have finer stems than those
seeded at lower rates. Lower seeding rates
are recommended for BMR varieties,
because finer stems coupled with lower
lignin concentrations increase the likelihood
of lodging (laying down). Sorghums should
not be sown until the soil temperature
reaches 60° F, which normally occurs
by mid-May in most of New Mexico.
Recommended seeding rates for pastures
are 20 to 40 pounds per acre.

Antiquality factors associated with
sorghums. Prussic acid poisoning is caused
when animal are fed immature sorghum
forage (including Johnsongrass, which is a
perennial weed); by regrowth after harvest or
grazing; or when plants are stressed by cool
weather, herbicide injury, drought stress and
frost. Death can occur within 15 minutes.
Avoid grazing sorghums until plants are 24
to 30 inches tall. After plants recover from
stress, check their base to see if new growth,
less than 24 inches tall, is present. Rapid,
immature growth is more palatable to
grazing livestock, but it also is highly toxic. It
is best not to graze sorghums in the fall until at least three days after the plants are
completely frozen down to protect livestock
from new growth. Prussic acid is short-lived
in stored sorghum forage, dissipating from
hay or silage within a month after harvesting.
NMSU has more information on prussic
acid in Guide B-808, “Livestock Poisoning
from Prussic Acid”.

Nitrate toxicity is another concern for
sorghum pasture and hay but not as much
for silage. Actually, any plant can accumulate
toxic nitrate levels, although it is most
common with annual grasses (warm- or coolseason).
Sorghums are prone to accumulate
nitrates, because they grow rapidly and
typically receive high rates of nitrogen
fertilizer. Drought stress also is commonly
associated with toxic forage nitrate levels.
When moisture is limiting, plants continue
to take nitrogen up from the soil, but they
are not able to convert it from nitrate to
protein. Thus, nitrate accumulates in older
and less photosynthetically active plant parts,
which usually are lower to the ground (e.g.,
the lower one-third of stems). Additionally,
plants that grow rapidly due to recent
irrigation or precipitation might take up
nitrogen faster than they can assimilate it,
particularly during cool, overcast weather.

In grazing situations, livestock prefer the
newer growth near the top of the plant.
However, hungry animals are not as
discriminating and might consume older
plant parts that are toxic. While the ensiling
process can reduce nitrate levels by as much
as 60 percent, nitrates do not dissipate from
forage stored as hay. Feeding greenchop is
most dangerous because animals cannot
avoid less palatable parts (stems and older
leaves are most toxic) like they can when
grazing or feeding on hay. Suspect forage
should be tested and, if toxic levels are
found, diluted with hay having low protein
content and/or fed with a concentrated
energy supplement, such as grain. High
nitrates in forage harvested for hay or greenchop can be avoided somewhat by
raising the cutting height to leave lower stem
portions in the field. Nitrate toxicity
generally is not a problem for monogastric
animals (horses, pigs). But levels greater than
about 3,000 parts per million (ppm) on a
dry matter basis can be toxic for ruminants
(cattle, sheep, goats), particularly if they are
under stress from illness, hunger, pregnancy
or lactation. Healthy animals can be slowly
acclimated to higher forage nitrate levels.
Concentrations above 6,000 ppm are
potentially toxic and should never be the
only feed source. Concentrations of 9,000
ppm and above often will lead to death
(see Guide B-807, “Nitrate Poisoning of
Livestock”).

Finally, sorghums also cause sorghum
cystitis-ataxia syndrome in horses. The same
compounds that are precursors to prussic
acid are thought to cause cystitis-ataxia.
Affected horses might exhibit urinary
incontinence due to nerve damage in the
urinary tract. Prolonged exposure leads to
posterior ataxia or incoordination and
numbness in the hindquarters. Further,
urinary stasis (the inability to void urine)
can result in urinary tract infections that
may lead to kidney infection. Horses
exhibiting symptoms can be treated with
antibiotics for urinary tract infections, but
if ataxia is present, recovery is very unlikely.
Guide B-704, “Sudangrass and Sorghum
Sudan Hybrid Poisoning of Horses” provides more information.

Pearl millet (Pennisetum typhoides) is
another choice for lower elevations, but it
does not perform well on soils high in
calcium. This species will not yield as much
as the sorghums, but it is safe for horses and
does not cause prussic acid poisoning.

Foxtail, German or Italian millet (Setaria italica) might provide temporary
summer pasture in New Mexico’s higher
elevations. Foxtail millet is less productive
than pearl millet and its shallow root system makes it easy for grazing animals
to uproot. As plants mature, they can
accumulate setarian, a compound that
acts as a diuretic in horses, causing
excessive urination. This compound can
lead to kidney problems and also has been
implicated in liver, bone and joint damage,
especially if the foxtail is the only hay
source for the horses. If symptoms are
observed early, removing millet hay from
the diet might correct the problem. More
information on all species of millet can be
found in Guide A-414, “Millet Production”.

Crop residues. Other forage sources
for grazing include plant residues after
grain harvest or cotton harvest that can
be used to defer grazing on small grains or
stockpiled pastures. Except for the seed
found in cotton remnants, these materials
generally are lower in quality, because
they are no longer actively growing. They
also are overmature and weathered. In
the case of grain crops, the energy was
removed by previous harvest. Thus, some
supplementation might be necessary, particularly for actively growing or
producing livestock.

Establishing Irrigated Pastures

Seed and plant stock selection. When
establishing an irrigated pasture, use the
best quality seed or planting stock available
to improve your chances of obtaining a
uniform, productive and persistent stand.
Once a species or combination of species is
chosen, variety selection is critical to get the
best genetics for your irrigated pasture
system. Use certified or plant variety
protected seed stocks to ensure the genetics
in the bag are true to the variety name (see
Guide A-131, “Certified Seed”). Read the
seed label (Guide A-216, “Know What is in a
Bag of Seed”), because several factors listed
involve seed quality and directly affect the
pasture species performance. The test date on
the label must be within the previous nine months for the seed to be sold legally in
New Mexico. Seed purity affects seeding rate
and stand uniformity as well as establishment
of weeds and undesirable crop species. High
inert matter, which includes stems, chaff, dirt
and rocks, usually is due to inefficient or
poorly developed seed-cleaning techniques.
Higher seeding rates must be used, increasing
seed costs. Excessive inert matter also
interferes with seed distribution, because it
can plug planting equipment or restrict seed
flow. Weeds and other crop species compete
for water, space and nutrients and reduce
forage production and quality. A relatively
weed-free field can be contaminated with
weeds, if seed containing weed seeds is sown.
Be sure that no noxious weeds are listed on
the label. Germination also is important for
determining the seeding rate and obtaining a
uniform stand. Seeding rate of many species
is given as pure live seed (PLS, calculated as
purity X germination). Seeding rates for
many warm-season grasses are given as
PLS values because they generally are very
chaffy (high inert matter) and have low
germination rates. Germination is affected
by crop species and seed dormancy, age,
damage, weathering and storage conditions.
However, even seeds that will germinate
might not have enough energy to produce
viable plants. Seedling vigor might be
affected by the same factors as germination.
Seed treatments are beneficial to seed
delivery, legume inoculation and protection
from seedling diseases and insects.

Preplant fertility and legume
inoculation. Before ground is broken for a
new pasture, a soil sample should be taken
and submitted for analysis. Guide A-114, “Test Your Soil” gives information about
soil sampling and testing. If sowing a
monoculture grass pasture, apply 20 to
25 pounds per acre of starter nitrogen to
help the grass get established. If planting a
grass-legume mixture, pay attention to the
phosphorus and potassium recommendations.
Legumes have the ability to fix nitrogen from the atmosphere. If inoculated with the
proper bacteria, they can meet their own
nitrogen requirement and provide nitrogen
to the companion grass (Guide A-129,
“Nitrogen Fixation by Legumes”). Adding
excessive nitrogen at establishment will
inhibit nitrogen-fixing nodule formation.
Without good nodulation, legumes will
produce stunted, yellow plants typical of
nitrogen deficiency, necessitating the addition
of supplemental nitrogen. Natural inoculation
can occur if the legume has been grown in the
field within the previous five years. However,
if there is any doubt, it is best to inoculate and
not use any preplant nitrogen.

Different legume species need different
bacteria, and the cost of inoculum is
relatively low compared to the cost of
nitrogen fertilizer. Commercially available
seed of many legumes will be pretreated.
The treatment date should be within the
previous year. If untreated seed is
purchased, inoculate the seed just before
planting. Be sure to use the inoculant
strain labeled specifically for the legume to
be planted. Apply the inoculum evenly to
the seed. Be sure to follow the instructions
on the inoculum package, including those
related to using a sticker to ensure uniform
contact between the seed and the
inoculant. Beware of using carbonated soft
drinks, 10 percent syrup mixtures or other
homemade stickers, because they might be
too acidic or alkaline and kill the bacteria.
When adding a liquid sticker, don’t get the
seed too wet or it will become clumpy.
Alfalfa seed should just feel sticky, and it
must be uniformly moist. Mixing by hand
in a large bucket, using a hoe in a larger
pan or using a cement mixer are equally
effective for a uniform treatment. More
information about legume inoculation can
be found in Guide A-130, “Inoculation
of Legumes”.

Land preparation. Proper land
preparation is important for establishing and
maintaining an irrigated pasture. The field should be prepared so it provides for the best
use and uniform distribution of water. The
type of irrigation system and soil condition
determines how much land preparation is
necessary. With sprinkler systems, the land
need only be level enough to allow easy
operation of the sprinklers and other
equipment. Flood and furrow irrigation, on
the other hand, require the land to be level
across the flow pattern, with the proper slope
for water to flow freely, while allowing
sufficient time for infiltration.

Another aspect of land preparation
involves developing a firm, smooth seedbed
so that planting depth can be regulated and
good seed-to-soil contact can be achieved.
Most perennial forage crops have small seeds
and should be planted no deeper than one-half
inch in heavy soil or up to an inch in
sandier soils (Figure 5). Uneven ground will
cause some seeds to be planted too deep, and
the new seedlings will not have enough
energy to emerge and begin photosynthesis.
It also is difficult to regulate planting depth
in loose or cloddy seedbeds. Seed sown at the surface of loose seed beds can be displaced by
irrigation water, leaving unsown areas for
weed infestation. Additionally, seed might be
at the correct depth, but poor contact with
soil particles limits access to water and
nutrients and decreases root-anchoring
strength when seedbeds are loose.

Planting time. Time of seeding is
determined largely by soil temperature and
species to be sown. Warm-season plants
germinate and emerge most rapidly when
soil temperature is above 55° F; cool-season
plants germinate and emerge when the soil
temperature reaches 45° F. Warm-season
species should be planted from spring to
midsummer (mid-May through July). This
allows sufficient time for the crop to
establish a good root system before freezing
temperatures occur. While cool-season
perennial species can be sown in the spring,
several factors make late summer planting
(mid-August to late September, depending
on location) more desirable. Late summer
seedings give the plants time to establish
fully and be ready to graze the following spring. Also, there usually is less weed
competition in fall than in spring; more time
is available to control weeds that germinate
during summer. And, while some summer
weeds might germinate after planting, not
many will have time to produce seed before
frost. Finally, evapotranspiration and wind
generally are less in the fall, allowing for
lower water requirements. Late summer
seedings need to be early enough to allow
plants to establish before freezing. Generally,
six to eight weeks are needed for fall
establishment.

Planting methods. Most pasture species
are established by seeding. But certain crops
like some of the improved bermudagrasses
must be established vegetatively. Vegetative
planting requires special operations and
equipment. The sprigs (vegetative planting
material) must be vigorous and healthy.
Plant them as soon as possible after
harvesting, because they do not store well.
Sprigs may be scattered and covered by light
disking or rototilling, or they can be planted
with a sprigging machine. Sprigging
machines provide more uniform sprig
distribution and covering, but they might
not always be readily available. Sprigging
and then irrigating are a common practice
to improve sprig-to-soil contact.

When possible, seeding is more
desirable than vegetative planting because
of availability and equipment and planting
material costs. With conventional tillage,
many pasture species can be sown either
by drilling or broadcasting. Both methods
provide uniform seed distribution, but
properly set drills and air-seeders with packer
wheels provide better seed coverage in the
same operation. Seed left on the surface can
be displaced by wind and water, removed by
birds or rodents, or die due to lack of seed-to-soil contact. Broadcast plantings must be
covered with a harrow or roller but neither
provides covering as well as packer wheels on
a drill or air-seeder (Figure 6). Generally,
harrowing or rolling is done in a second operation, but equipment is available that
will broadcast and harrow or roll in one
operation. Broadcast seeding is easier and
takes less time than drilling, but this
advantage can be more than offset through
seed loss by displacement and the need for
secondary operations. Hydroseeding also
might be an option for establishing smaller
pastures. Hydroseeders are available at many
larger landscaping companies.

Figure 6. Relative effectiveness of using different seeding equipment and methods to achieve
a forage crop stand (Source: Tesar, University of Michigan, 1984).

If land reconstruction is not needed to
improve conditions for irrigation, no-tillage or
minimum-tillage planting can save time and
money as compared with conventional tillage
operations. These practices also improve
moisture conservation, because the soil is
mulched with plant residue. No-till planting
does require a seed drill especially designed for
penetrating untilled ground, so be sure the
equipment is heavy enough to place the seed
at the proper depth. Existing vegetation must
be controlled to prevent competition and
allow new seedlings to establish. Initial
chemical applications should be made two
weeks before planting to remove the
established insects’ food sources and to
encourage them to migrate to another area so
that they won’t feed on the seed. Insecticide
seed treatments help overcome this problem.
Also, if the same forage species is reseeded,
disease pressure on seedlings might escalate,
especially for legumes. Metalaxyl seed
treatment is relatively effective for protecting
seedlings from many diseases. For no-till
planting, use the highest recommended
seeding rate.

Established grass pastures can be
renovated with legumes by either of two
methods, no-till in late summer or frostseeding
in late winter (early February to mid-March, depending on location). In either
situation, apply a chemical to burn down the
grass or remove as much top growth as
possible by grazing. Grazing probably is the
best option, and animals can remain in the
pasture until they begin biting or uprooting
the new seedlings. Once that happens, remove the animals and allow the new seedlings to
establish by reaching 25 percent bloom.

Irrigation. Preplant irrigation can
help overcome some problems with land
preparation and seed movement caused by
post-planting irrigation. Wetting the soil
breaks down clods and firms the seedbed,
improving seed-to-soil contact at planting
time. Soil crusting, which inhibits new
seedlings from emerging, also can be
prevented with pre-irrigation. But this
method also has disadvantages. Planting
must be done before the soil has dried too
much for satisfactory germination. If the soil
is too wet, there can be excessive soil
compaction and crusting. Knowing when the
soil is moist enough to plant, yet dry enough
to drive equipment over the field, is largely a
matter of experience. Also, because most
perennial forage crop seeds are small and
must be planted shallowly, desiccation of
new seedlings must be prevented by keeping
the top inch or so moist until emergence. Crusting also must be prevented, possibly
requiring more frequent irrigation just for
establishment. This should not be much of a
problem when using sprinkler irrigation,
which can apply lesser amounts of water
more frequently. But flood and furrow
irrigation systems are not as efficient and
small amounts of water cannot be applied.
Pre-irrigating might cause water to be in
short supply at another time during the
growing season.

Companion crops. Sometimes an
annual crop, usually a small-grained species,
is planted with a perennial pasture species as
a companion (also known as a nurse crop) to
protect it until it becomes established. This
practice is discouraged except under special
circumstances, such as when seedlings need
protection from wind or the soil is highly
erodible. The companion crop might protect
the pasture species from the wind and
provide an early hay or grain crop, but it
competes directly with the pasture species for water, nutrients, light and space, delaying
stand establishment drastically and possibly
resulting in a less uniform stand. Seeding
early enough in the late summer for plants to
establish a good root system and some top
growth is the best management option.
Producers also can consider no-till seeding
into residue from the previous crop to
protect the new seedlings.

Completing establishment. Once
seedlings have emerged from the soil, they
need special care to become established as a
productive, persistent pasture. Management
during the first growing season determines
the perennial pasture stand’s uniformity and
longevity. Adequate nutrients are essential.
Follow preplant soil test recommendations
for the species. Irrigation management also is
critical. There must be a compromise
between providing enough moisture for the
plant to rapidly grow and forcing the plant
to develop a good root system as it searches
for water. Too little irrigation causes the
plant to use too much energy for root system
development rather than top growth.
Desiccation also can lead to plant death. Too
much irrigation also is detrimental, because
some nutrients can be leached, root system
development is inhibited, and seedling
diseases are encouraged.

Weed control still will be a concern
because weeds compete for nutrients, water,
light and space. The best weed control
begins with a weed-free seedbed, assisted by
a uniform stand of the pasture plants that
can quickly establish ground cover. It still
might be necessary, however, to mow weeds
or control them with a herbicide labeled for
the weed and the forage crop(s). Be sure to
mow high enough to avoid clipping the
desirable species.

Grazing pastures too soon also can cause
problems. New pasture plants should be
allowed to become reproductive before being
harvested or grazed the first time. Allow
grasses to reach the early heading stage and
legumes to reach approximately 25 percent bloom. Manage grass-legume mixtures for
the legume. If a companion crop is sown to
protect the new seedlings, use grazing as with
a frost-seeding. Otherwise, harvest the
companion crop as hay to reduce shading
and competition. In either case, manage the
pasture to protect the new seedlings by not
grazing or clipping them until they are
mature enough.

Summary

Irrigated pastures can serve many valuable
purposes, such as generating income or
maintaining animals for work, pleasure or
aesthetics. Whatever the purpose, success
begins with good species selection and
establishment. Pasture species should be
well-adapted to the site where they will be
grown and suitable for their intended
purpose. The information provided in this
publication should be useful in the planning
and decision-making process. Other
resources also are available from your county Cooperative
Extension Service office or through New Mexico State University’s
College of Agricultural, Consumer and Environmental Sciences publications Web site at www.aces.nmsu.edu/pubs. Circular 586, “Grazing Systems and
Management of Irrigated Pastures in
New Mexico” provides information about
designing pasture systems, grazing techniques
and managing pastures for productivity,
persistence and animal health.

To find more resources for your business, home, or family, visit the College of Agricultural, Consumer and Environmental Sciences on the World Wide Web at aces.nmsu.edu.

Contents of publications may be freely reproduced for educational purposes. All other rights reserved. For permission to use publications for other purposes, contact pubs@nmsu.edu or the authors listed on the publication.

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